Digital transmission signal processing system and recording/reproducing system

ABSTRACT

A processing system and a recording/reproducing system for a digital signal including a digital video signal and a digital audio signal. Upon transmission, the digital signal is transmitted after time-base compression and modulation. The transmitted signal is received and demodulated. In the case where the signal is to be transmitted to a plurality of recording/reproducing systems, address signals designating ones of the plural recording/reproducing systems and a control signal for controlling the start/stop of recording are transmitted. The recording by the recording/reproducing system is controlled so that it is made with the same format in either normal-speed or high-speed mode or in either normal or multiple recording mode.

BACKGROUND OF THE INVENTION

The present invention relates to a system for transmitting a digitalvideo signal and recording the received video signal. More particularly,the present invention greatly extends the range of use of a digitalsignal recording/reproducing system by vastly reducing the recordingtime by transmitting a video signal in a compressed form, and furtherextends the range of use of a digital signal recording/reproducingsystem by making the number of signals to be recorded and a recording/reproducing time variable.

As an example of a digital magnetic recording/reproducing system(hereinafter referred to as VTR), a D2 format VTR is conventionallyknown. In such a conventional digital VTR, the elongation or shorteningof a reproducing time is possible by using variable-speed reproduction.However, the prior art reference does not at all disclose high-speedrecording in which a recording time is shortened to l/m, multiplerecording in which a plurality of signals are recorded, and thecompression/expansion of a recording/reproducing time.

The above-mentioned conventional digital VTR has a feature that a highquality reproduction is attained and there is no deterioration caused bydubbing. However, the shortening of a dubbing time is not taken intoconsideration. Therefore, for example, in the case where a two-hourprogram is to be recorded, two hours are required for dubbing, as well.Thus, inconveniences are encountered in using the conventional system.Also, the multiplexing of recording signals is not taken intoconsideration. Therefore, for example, when two kinds of programs are tobe simultaneously recorded or reproduced, two VTR's are required, whichproves to be another inconvenience is using the conventional system.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a digital VTR in whichhigh-speed recording onto a tape can be made with the same format asthat used in standard-speed recording, to provide a transmission signalprocessing system for transmitting at a high speed a video signal to berecorded by such a digital VTR, and to extend the range of use of thedigital VTR by shortening a recording time. For example, the digital VTRcan be used in such a manner that a two-hour program is recorded inabout ten minutes and is reproduced at a standard speed.

The above object is achieved as follows. A video signal and an audiosignal are subjected to time-base compression to l/m, bit compression tol/n, addition of a parity signal and modulation, and are thereaftertransmitted or output. The transmitted signal is received, is subjectedto demodulation, error correction, addition of a parity signal andmodulation, and is thereafter recorded, onto a magnetic tape whichtravels at a travel speed m times as high as that for normalreproduction, by use of a magnetic head on a cylinder which rotates at afrequency m times as high as that upon for normal reproduction. Thesignal on the magnetic tape traveling at a travel speed upon for normalreproduction is reproduced by a magnetic head on the cylinder whichrotates at a frequency upon for normal reproduction. The reproducedsignal is subjected to demodulation, error correction, bit expansion ofvideo and audio signals and D/A conversion, and is thereafter output.Address signals corresponding to a plurality of VTR's may be transmittedprior to a signal to be recorded. Further, control signals indicative ofthe start of recording and the stop of recording may be transmitted. Thetransmitted signals are received and error-corrected, and controls ofthe standby for recording, the start of recording and the stop ofrecording are made on the basis of the control signals.

With the above construction, since the video signal and the audio signalare time-base compressed to 1/m and bit-compressed to l/n, atransmission time is shortened to 1/m and a signal band turns to m/n.The time-base compressed and bit-compressed signal is transmitted afteraddition of a parity signal for error correction and modulation to acode adapted for a transmission path. The transmitted signal is receivedand demodulated. The detection of an error produced in a transmittingsystem and the correction of the error can be made using the addedparity signal. The error-corrected signal is added with a parity signalfor correction of an error produced in a magnetic recording/reproducingsystem and is modulated to a code adapted for the magneticrecording/reproducing system. Upon recording, since the rotationfrequency of the cylinder and the travel speed of the magnetic tape areincreased by m times, the recording onto the magnetic tape can be madeat an XM speed. Upon reproduction, by setting the rotation frequency ofthe cylinder and the travel speed of the magnetic tape to normal ones,the reproduction at a normal speed can be made. The reproduced signal iscode-demodulated. The detection of an error produced in the magneticrecording/reproducing system and the correction for the error can bemade on the basis of the parity signal. By bit-expanding the videosignal and the audio signal compressed by the transmission signalprocessing system, the original video and audio signal can be restored.The bit-expanded signal is converted into an analog signal by a D/Aconverter. Simultaneous and selective control of the start/stop ofrecording for a multiplicity of VTR's can be made in such a manner thatthe address signals corresponding to the VTR's are transmitted prior toa signal to be recorded, the correction for an error of the receivedsignal is made, required VTR's are brought into recording standbyconditions by the corrected address signals, and the controls for thestart of recording and the stop of recording are made by the transmittedcontrol signals.

Another object of the present invention is to provide a digital signalrecording/reproducing system in which multiple recording onto a tape canbe made with the same format as that used in standard recording so thatsimultaneous multiple reproduction is possible, and to extend the rangeof use of a digital VTR by compressing/ expanding arecording/reproducing time in accordance with the transmission rate of amultiplexed input/output signal and the number of signals in themultiplexed input/output signal.

This object is achieved as follows. There are provided means forselecting one or more desired signals from a time-base compressed andtime-division multiplexed digital input signal, and helical scanrecording means for making time-division multiplex recording of theselected signals with a time-base compressed speed after the selectedsignals are retained. There is further provided means for reproducingthe recorded signals with the rotation speed of a cylinder, a tape speedand so on being set to values proportional to the transmission rate of areproduction signal and the number of signals to be simultaneouslyreproduced and with the signal being time-base expanded or beingretained as time-base compressed.

With the above construction, N kinds of desired signals, selected fromthe multiplexed input digital signal and time-base compressed to l/K,are subjected to time-division multiplex recording with a time-basecompressed speed after the selected signals are retained. Uponreproduction, for example, if both the cylinder rotation speed and thetape speed are set to N/K times, a recording track and a reproducingtrack coincide with each other and the use of a reproducing time K/Ntimes as long as a recording time enables the reproduction of each ofthe N kinds of signals at a standard speed. Also, if both the cylinderrotation speed and the tape speed are set to (M×N)/K times, a recordingtrack and a reproducing track coincide with each other and the use of areproducing time as K/(M×N) times as long as the recording time enablesthe reproduction of each of the N kinds of signals at an XM speed. Inthe case where L kinds of signals are selected from among the N kinds ofreproduced signals and a processing speed at a reproduction signalprocessing circuit is set to L×M times as long as a standardreproduction processing speed, each of the L kinds of signals among theN kinds of multiple-recorded signals is output at a speed M times ashigh as a standard speed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a digital transmission signal processingsystem and a recording/ reproducing system according to an embodiment ofthe present invention;

FIG. 2 is a block diagram of a recording/ reproducing system accordingto another embodiment of the present invention;

FIG. 3 is a diagram for explaining the conventional parity addingmethod;

FIG. 4 is a block diagram of a recording/ reproducing system accordingto still another embodiment of the present invention;

FIG. 5 is a block diagram of a digital transmission signal processingsystem and a recording/ reproducing system according to a furtherembodiment of the present invention;

FIG. 6 shows the format of control signals used in one application ofthe present invention;

FIG. 7 is a block diagram of a still further embodiment of the presentinvention;

FIG. 8 shows one example of the specification of signals to be recorded;

FIG. 9 is a block diagram of a further embodiment of the presentinvention;

FIGS. 10, 11 and 12 are block diagrams of different examples ofapplications of the present invention;

FIG. 13 is a block diagram for explaining one example of the operationof the embodiment shown in FIG. 7;

FIG. 14 is a timing chart showing the waveforms of signals involved inthe example shown in FIG. 13;

FIG. 15 is a block diagram for explaining another example of theoperation of the embodiment shown in FIG. 7;

FIG. 16 is a timing chart showing the waveforms of signals involved inthe example shown in FIG. 15;

FIG. 17 is a table showing some applications of the examples shown inFIGS. 13 and 15;

FIG. 18 is a block diagram of a still further embodiment of the presentinvention; and

FIGS. 19 and 20 are signal diagrams for explaining different operationsof the embodiment shown in FIG. 18.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the present invention will now be explained by use ofFIG. 1. In the figure, reference numerals 1 and 40 denote magnetictapes, numerals 2, 3, 41 and 42 magnetic heads, numerals 4 and 43cylinders, numerals 5 and 44 capstans, numerals 10 and 50 servo controlcircuits, numerals 20, 31 and 60 demodulation circuits, numerals 21, 32and 61 error correction circuits, numerals 22 and 23 compressioncircuits, numerals 24 and 33 parity addition circuits, numeral 25 and 34modulation circuits, numerals 26 a transmission circuit, numeral 27 atransmission path, numeral 30 a reception circuit, numerals 62 and 63expansion circuits, numerals 64 and 65 D/A conversion circuits, numeral70 a video signal output terminal, and numeral 71 an audio signal outputterminal.

Firstly, the operation of a transmission signal processing system willbe explained. Digital video and audio signals recorded on the magnetictape 1 are reproduced by the magnetic heads 2 and 3 mounted on thecylinder 4 and are input to the demodulation circuit 20. The magnetictape 1 travels by virtue of the capstan 5. The travel speed of themagnetic tape 1 and the rotation frequency of the cylinder 4 are, forexample, ten times as high as the tape travel speed and the cylinderrotation speed for normal reproduction. Accordingly, the signal input tothe demodulation circuit 20 is a signal time-compressed to one tenth thenormal tape travel speed. For example, a 120-minute signal recorded onthe magnetic tape 1 can be reproduced in 12 minutes.

Generally, in the case where a digital signal is to be recorded on amagnetic recording medium, the signal is recorded after having beenmodulated into scrambled NRZ code, M² code or the like. The demodulationcircuit 20 performs a demodulation processing, that is, a signalprocessing for restoring the thus modulated signal into original digitaldata. The signal demodulated by the demodulation circuit 20 is input tothe error correction circuit 21 in which erroneous data produced in amagnetic recording/ reproducing process is detected and correction forthe erroneous data is made. Further, the signal is separated into avideo signal and an audio signal which are in turn input to thecompression circuits 22 and 23, respectively. The video signal isbit-compressed through, for example, discrete cosine conversion. Theaudio signal is bit-compressed through, for example, non-linearquantization or differential PCM. As a result, the transmission rate ofthe video signal and the audio signal in total is reduced to, forexample, one twentieth of that for normal transmission.

Output signals of the compression circuits 22 and 23 are input to theparity addition circuit 24 for performing a signal processing whichincludes adding a parity signal for error correction and outputting thevideo signal and the audio signal serially in accordance with atransmission format. A serial output signal of the parity additioncircuit 24 is input to the modulation circuit 25. In the modulationcircuit 25, the serial signal is modulated in accordance with thecharacteristic and the frequency band of the transmission path 27. Forexample, in the case where the signal is transmitted in an electric waveform, quadruple phase shift keying (QPSK) is made. The modulated signalis input to the transmission circuit 26 from which it is output to thetransmission path 27.

As apparent from the foregoing explanation of the operation of thetransmission signal processing system, it is possible to transmit asignal at a speed which is ten times as high as a normal speed.

The above embodiment has been shown in conjunction with the case where asignal from the VTR is reproduced. However, a signal source is notlimited to the VTR and may include a magnetic disk device, an opticaldisk device or the like.

Next, explanation will be made of the operation of the VTR for receivingand recording the transmitted signal. The signal transmitted from thetransmission signal processing system is received by the receptioncircuit 30. The received signal is input to the demodulation circuit 31.The demodulation circuit 31 is provided corresponding to theaforementioned modulation circuit 25 and demodulates the signal to theoriginal signal. The demodulated signal is input to the error correctioncircuit 32 in which the detection of and the correction for an errorproduced in the transmission path 27 are made on the basis of the paritysignal added by the parity addition circuit 24. At this time, in thecase where the S/N ratio of the transmission system is not sufficient sothat complete correction for the error is impossible, correction is madethrough, for example, signal replacement, by use of the signalcorrelation.

An output signal of the error correction circuit 32 is input to theparity addition circuit 33. In the parity addition circuit 33, a paritysignal for detecting an error produced in a recording/ reproducingprocess and making correction for the error is added. The parity-addedsignal is input to the modulation circuit 34. In the modulation circuit34, the signal is modulated to scrambled NRZ code, M² code or the likeas mentioned above. The modulated signal is recorded on the magnetictape 40 by the magnetic heads 41 and 42 mounted on the cylinder 43.

Since the signal supplied to the magnetic heads 41 and 42 is a signalwhich is time-base compressed to one tenth as compared with a signal fornormal operation, the servo control circuit 50 controls the cylinder 43and the capstan 44 so that the rotation frequency of the cylinder 43 andthe travel speed of the magnetic tape 40 become ten times as high asthose for normal recording. Also, in order to record a predeterminedsignal at a predetermined position on the magnetic tape 40,synchronization information is detected from the received signal tocontrol the phase of rotation of the cylinder 41 on the basis of thedetected synchronization information.

Next, the operation of the VTR for reproducing the thus recorded signalwill be explained. Upon reproduction, the travel speed of the magnetictape 40 and the rotation frequency of the cylinder 43 are set to thosefor normal reproduction. The reproduced signal is input to thedemodulation circuit 60. The demodulation circuit 60 is providedcorresponding to the modulation circuit 34 and demodulates the modulatedsignal. The demodulated signal is input to the error correction circuit61 in which the detection of an error produced in the magneticrecording/reproducing system and the correction for the error are madeon the basis of the parity signal added by the parity addition circuit33. In the case where there is an error which cannot be corrected, theerror is properly corrected by use of the signal correlation. Also, thesignal is output after having been separated into a video signal and anaudio signal.

The video signal is input to the expansion circuit 62. The expansioncircuit 62 is provided corresponding to the compression circuit 22 andrestores the compressed video signal into the original video signal. Anoutput signal of the expansion circuit 62 is input to the D/A conversioncircuit 64 and is converted thereby into an analog video signal which isin turn output from the terminal 70.

The audio signal is input to the expansion circuit 63. The expansioncircuit 63 is provided corresponding to the compression circuit 23 andrestores the compressed audio signal into the original audio signal. Anoutput signal of the expansion circuit 63 is input to the D/A conversioncircuit 65 and is converted thereby into an analog audio signal which isin turn output from the terminal 71.

In the foregoing, the embodiment of the present invention has been shownand the operation thereof has been explained. According to the presentinvention, a video signal and an audio signal over a long time can betransmitted and recorded in a short time, thereby making it possible toextend the range of use of the digital VTR.

Another embodiment of the present invention is shown in FIG. 2. FIG. 2is partially similar to FIG. 1. The same parts in FIG. 2 as those inFIG. 1 are denoted by the same reference numerals as those used in FIG.1 and detailed explanation thereof will be omitted. The embodiment shownin FIG. 2 concerns a VTR in which a signal transmitted/received at ahigh speed can be recorded while being monitored.

In FIG. 2, reference numeral 80 denotes a change-over switch, numeral 81an error correction circuit, and numeral 82 a memory circuit. Anerror-corrected video signal output from the error correction circuit 81is input through the memory circuit 82 to a terminal R side of thechange-over switch 80 which is selected upon recording. The memorycircuit 82 has a memory capacity for at least one field. The videosignal received at a high speed is stored into a memory of the memorycircuit 82 with the number of frames being reduced. The stored signal isread from the memory at a normal speed and is input to an expansioncircuit 62.

Upon reproduction, a video signal output of an error correction circuit61 is input to a terminal P side of the change-over switch 80 which isselected upon reproduction. Accordingly, the operation of the embodimentof FIG. 2 upon reproduction is similar to that of the embodiment shownin FIG. 1.

In the embodiment shown in FIG. 2, upon recording, the video signaloutput from the error correction circuit 81 is input to the expansioncircuit 62 through the memory circuit 82. Alternatively, an outputsignal of a modulation circuit 34 may be input to a demodulation circuit60 through a memory circuit. Also, in the case where the operating speedof the demodulation circuit 60 or the error correction circuit 61 leavesa margin, a memory circuit may be properly placed at a post stage. Or,in the case where the storage capacity of the error correction circuit61 or the expansion circuit 62 leaves a margin, the circuit may be usedas a memory circuit or any additional memory circuit may be omitted.

As has been explained above, the embodiment shown in FIG. 2 makes itpossible to record a received video signal while monitoring it in theform of a picture having a reduced number of frames.

In the embodiment shown in FIG. 1, the parity signal is added in orderto detect and correct an error which may be produced in the transmissionsystem or the magnetic recording/reproducing system. One example of aparity adding method is shown in FIG. 3 in conjunction with the case ofa D2 format VTR. In the D2 format VTR, a signal for one field is dividedinto a plurality of segments for signal processing. FIG. 3 shows onesegment. In FIG. 3, reference numeral 90 represents a group of videodata, numeral 91 a group of outer code parities, and numeral 92 a groupof inner code parities. Firstly, outer code parities are added for dataof the matrix-like arranged video data group 90 which lie in a verticaldirection in FIG. 3. Thereafter, inner code parities are added for dataof the video data group 90 and the outer code parity group 91 lying in ahorizontal direction in FIG. 3, thereby producing a signal to berecorded. Though detailed explanation of the generation of parities willbe omitted herein, the parities are generated in accordance with agenerating function G(x).

In the embodiment shown in FIG. 1, if the same parity generation manneris employed by the parity addition circuits 24 and 33, the errorcorrection circuits 32 and 61 may hold the most part thereof in common.Namely, since the error correction circuits 32 and 61 are circuits whichare respectively used for recording and for reproduction, it is possibleto reduce the circuit scale or size by using the most part of thecircuits 32 and 61 in common.

Further, in the case where the same parity generation manner is employedby the parity addition circuits 24 and 33 in the embodiment shown inFIG. 1, it is possible to further reduce the circuit scale or size ofthe recording/reproducing system. The construction in that case is shownin FIG. 4 as still another embodiment of the present invention. FIG. 4is partially common to FIG. 1 or 2. The parts in FIG. 4 common to thosein FIG. 1 or 2 are denoted by the same reference numerals as those usedin FIG. 1 or 2 and detailed explanation thereof will be omitted.

The embodiment shown in FIG. 4 is based on a concept that an errorproduced in a transmission system and an error produced in a magneticrecording/reproducing system are simultaneously detected and correctedby an error correction circuit 61. Accordingly, a signal received by areception circuit 30 is demodulated by a demodulation circuit 31 and isinput to a modulation circuit 34 without being subjected to errorcorrection and parity addition. The subsequent processing is the same asthat in the embodiment shown in FIG. 1 or 2. Namely, a reproduced signalis input to the error correction circuit 61 after demodulation by ademodulation circuit 60. As mentioned above, an error produced in thetransmission system and an error produced in the magneticrecording/reproducing system are simultaneously detected and correctedby the error correction circuit 61 in the reproducing system.

In the embodiment shown in FIG. 4, the error correction circuit 32 andthe parity addition circuit 33 can be removed as compared with theembodiment shown in FIG. 1 or 2, thereby making it possible to reducethe circuit scale.

Though having not been mentioned in the foregoing embodiments, in ahelical scan VTR as shown, since a signal becomes discontinuous when atrack jump is made upon reproduction, the recording is made with anamble signal being added to the heading portion of a signal. Since theaddition of an amble signal is employed in the D2 format VTR, detailedexplanation thereof will be omitted. Also, in order to define a startingposition of a signal, a synchronizing signal is properly added. Sincethe addition of a synchronizing signal is known in, for example, the D2format VTR, detailed explanation thereof will be omitted.

In the embodiment shown in FIG. 1, the addition of an amble signal maybe made by the parity addition circuit 24. Alternatively, it may be madeon the recording/reproducing system side in order to enhance theefficiency of use of the transmission path 27. In this case, theaddition of an amble signal can be made by the parity addition circuit33. As for the embodiment shown in FIG. 4, in the case where theaddition of an amble signal is to be made on the recording/reproducingsystem side, the amble signal can be added by the modulation circuit 34.In the case where the addition of an amble signal is made on therecording/reproducing system side, it is possible to enhance theefficiency of use of the transmission path 27. On the other hand, in thecase where the addition of an amble signal is made on the transmissionsignal processing system side, the lowering of the cost of a VTR can beattained as a great effect when a signal is sent to a multiplicity ofVTR's simultaneously.

FIG. 5 shows a further embodiment of the present invention in which thefurther reduction of the circuit scale of a VTR on the receiving sideand hence the further lowering of the cost can be attained in the casewhere a signal is sent to a multiplicity of VTR's simultaneously.

FIG. 5 is partially common to FIG. 1, 2 or 4. The parts in FIG. 5 commonto those in FIG. 1, 2 or 4 are denoted by the same reference numerals asthose used in FIG. 1, 2 or 4 and detailed explanation thereof will beomitted. In FIG. 5, reference numeral 100 denotes a modulation circuit.The embodiment shown in FIG. 5 is based on a concept that a signalprocessing required upon a recording mode of a VTR is performed on thetransmitting side. Namely, modulation adapted for magneticrecording/reproduction, for example, a signal processing correspondingto the modulation circuit 34 shown in FIG. 4 is performed on thetransmission signal processing system side. After parities have beenadded by a parity addition circuit 24 of the transmission signalprocessing system, the modulation adapted for the magneticrecording/reproduction is performed by the modulation circuit 100.Therefore, modulation adapted for transmission is performed by amodulation circuit 25. A modulation system employed by the modulationcircuit 100 is suitable for a system which does not cause the extensionof a frequency band by modulation, for example, scrambled NRZ. A signalmodulated by the modulation circuit 25 is transmitted to a transmissionpath 27 through a transmission circuit 26 in a manner to that in theembodiment shown in FIG. 1.

The signal received by a reception circuit 30 through the transmissionpath 27 is input to a demodulation circuit 31 in which the signal issubjected to demodulation corresponding to the modulation circuit 25.Since the signal demodulated by the demodulation circuit 31 is one whichhas already been subjected by the modulation circuit 10 to themodulation adapted for the magnetic recording/reproduction, the signalis recorded on a magnetic tape 40 by magnetic heads 41 and 42 as it is.As a result, the same recording as that in the embodiment shown in FIG.4 is made. An operation upon reproduction is similar to that in theembodiment shown in FIG. 4.

As apparent from the above, the present embodiment makes it possible toremarkably reduce the circuit scale of the VTR.

According to one of applications of the present invention, it ispossible to transmit a signal from a transmission signal processingsystem to a multiplicity of VTR's through a transmission pathsimultaneously and at a high speed, as has already been mentioned. Inthis case, it is difficult to control a multiplicity of VTR'ssimultaneously. Further, it is required to make a control which causesspecified ones of the VTR's to perform recording operations andspecified others of the VTR's not to perform recording operations. Atechnique for realizing such a control will be shown just below.

For the above purpose, control signals are transmitted prior totransmission of a signal to be recorded. One example of the controlsignals is shown in FIG. 6. In the figure, reference numeral 110 denotesa synchronizing signal, numeral 111 an ID signal indicative of a controlto be made, numeral 112 an address signal indicative of a VTR to becontrolled, numeral 113 a control signal for bringing a VTR designatedby the address signal 112 into a recording mode, numeral 114 a controlsignal for stopping the recording, numerals 115 and 116 blank signals,and numeral 120 a recording signal to be actually recorded.

The ID signal 111 indicating the transmission of the address signals 112indicative of VTR's in which a signal is to be recorded, is transmittedat a predetermined position relative to the synchronizing signal 110 tobring each VTR into a standby condition. After all the address signalshave been transmitted, the ID signal 113 is transmitted to start therecording of the signal 120 in the designated VTR's. After the signal120 has been transmitted, the ID signal 114 for controlling the stop ofrecording is transmitted. Each of the blank signals 115 and 116 is asignal for conforming a signal transmission format to the othertransmission signal and is therefore an insignificant signal portion.

In the embodiments shown in FIGS. 1 and 5, those control signals areproduced by a control signal generation circuit 130 and are transmittedwith parities which are added by the parity addition circuit 24 formaking correction for an error produced during transmission.

In the VTR shown in FIG. 1, the control signals are detected by acontrol circuit 131 after the reception by the reception circuit 30, thedemodulation by the demodulation circuit 31 and the correction by theerror correction circuit 32 for an error produced during transmission tomake a control for the recording and the stop of recording in therecording/reproducing system.

In the case of the VTR's shown in FIGS. 4 and 5, an output signal of thedemodulation circuit 31 is input to the error correction circuit 61 forcorrecting an error produced during transmission and error-correctedcontrol signals are input to a control circuit 131. In a change-overcircuit 132, the terminal R side for selecting an output signal of thedemodulation circuit 31 is selected upon recording and the terminal Pside for selecting an output signal of the demodulation circuit 60 isselected upon reproduction.

As apparent from the foregoing, the present embodiment makes it possibleto control a multiplicity of VTR's selectively and simultaneously.

Also, the use of the change-over circuit 132 and a memory circuit makesit possible to record a signal while monitoring it in the form of apicture having a reduced number of frames, as explained in conjunctionwith the embodiment shown in FIG. 2.

Next, a still further embodiment of the present invention will beexplained by use of FIG. 7. In the figure, reference numeral 301 denotesan input terminal for standard analog video signal, numeral 302 an inputterminal for standard digital video signal, numeral 303 an inputterminal for high-speed digital video signal, numeral 305 a recordingsystem mode change-over switch, numeral 306 a recording systemchange-over signal generation circuit, numeral 310 an A/D converter,numeral 320 a change-over circuit, numeral 330 a data compressioncircuit, numeral 340 a change-over circuit, numeral 350 a recordingsystem signal processing circuit for performing a signal processingwhich includes addition of error correction code and modulation forrecording, numeral 370 a cylinder, numeral 371 a magnetic tape, numerals372 and 372' magnetic heads, numeral 380 a reproducing system signalprocessing circuit for performing a signal processing which includesdemodulation for reproduction, error detection and error correction.Numeral 390 denotes a change-over circuit, numeral 400 a data expansioncircuit, numeral 420 a D/A converter, numeral 431 an output terminal forstandard analog video signal, numeral 432 an output terminal forstandard digital video signal, numeral 433 an output terminal forhigh-speed digital video signal, numeral 435 a reproducing system modechange-over switch, and numeral 436 a reproducing system change-oversignal generation circuit.

The present embodiment is an example of a digital magneticrecording/reproducing system which has recording modes of standard-speedrecording and high-speed recording and reproduction modes ofstandard-speed reproduction and high-speed reproduction. FIG. 8 showsone example of the specification of input video signals.

Firstly, explanation will be made of standard-speed recording. A digitalsignal into which an analog video signal inputted from the inputterminal 301 is converted by the A/D converter 310 or an equivalentdigital signal which is input from the input terminal 302, is switchedor selected by the change-over circuit 320, is subjected to apredetermined data compression processing by the data compressioncircuit 330 and is thereafter input to a terminal 340a of thechange-over circuit 340. In the change-over circuit 340, a change-overto connect the terminal 340a and a terminal 340c is made by achange-over signal from the recording system change-over signalgeneration circuit 306. Thereby, the data-compressed signal is input tothe recording system signal processing circuit 350. In the recordingsystem signal processing circuit 350, a signal processing such aschannel division, addition of error correction code and modulation forrecording is performed at a predetermined processing clock adapted forthe data-compressed signal. Thereafter, the signal is supplied to themagnetic heads 372 and 372' mounted on the cylinder 370 so that it isrecorded onto the magnetic tape 371. The cylinder 370 and the magnetictape 371 are controlled by a servo control circuit 360. The servocontrol circuit 360 controls a cylinder motor and a capstan motor so asto provide a cylinder rotation speed and a tape speed for standard speedand so as to be synchronized with the input video signal.

Next, explanation will be made of high-speed recording. A high-speeddigital video signal input from the input terminal 303 is sent to aterminal 340b of the change-over circuit 340. Since the high-speeddigital video signal is a signal which has already been subjected to adata compression processing, it is not necessary to pass the signalthrough the data compression circuit 330. A change-over to connect theterminal 340b and the terminal 340c is made by a change-over signal fromthe recording system change-over signal generation circuit 306 so thatthe high-speed digital video signal is input to the recording systemsignal processing circuit 350. In the recording system signal processingcircuit 350, a signal processing similar to that in the case of thestandard-speed recording is performed at a predetermined processingclock adapted for the high-speed digital video signal. Thereafter, thesignal is supplied to the magnetic heads 372 and 372' mounted on thecylinder 370 so that it is recorded onto the magnetic tape 371. Thecylinder 370 and the magnetic tape 371 are controlled by the servocontrol circuit 360. The servo control circuit 360 control the cylindermotor and the capstan motor so as to provide a predetermined cylinderrotation speed and a predetermined tape speed and so as to besynchronized with the input video signal.

In the present invention, the recording onto the tape can be made withsubstantially the same format as in both the standard-speed recordingand the high-speed recording, thereby making it possible to greatlyreduce a recording time in the high-speed recording mode.

Next, explanation will be made of a signal processing upon reproduction.In the present embodiment, the recording pattern on the magnetic tape isthe same whichever of the standard-speed recording and the high-speedrecording is selected as a recording mode. Therefore, eitherstandard-speed reproduction or high-speed reproduction can be selectedirrespective of the recording mode.

Firstly, the standard-speed reproduction will be explained. The servocontrol circuit 360 controls the cylinder motor and the capstan motor sothat a cylinder rotation speed and a tape speed for standard speed areprovided. A signal reproduced by the magnetic heads 372 and 372' isinput to the reproducing system signal processing circuit 380. In thereproducing system signal processing circuit 380, a signal processingsuch as demodulation for reproduction, channel synthesis, errordetection and error correction is performed at a predeterminedprocessing clock adapted for the standard-speed reproduction.Thereafter, the signal is supplied to a terminal 390a of the change-overcircuit 390. In the change-over circuit 390, a change-over to connectthe terminal 390a and a terminal 390c is made upon standard-speedreproduction by a change-over signal from the reproducing systemchange-over signal generation circuit 436. Thereby, the reproducedsignal is supplied to the data expansion circuit 400. In the dataexpansion circuit 400, a signal processing reverse to the datacompression processing upon recording is performed so that the signal isrestored to the original signal. Thereby, the original transmission rateis restored. The data-expanded reproduction signal is sent to the D/Aconverter 420 on one hand to be output as an analog video signal fromthe output terminal 431 after D/A conversion and is sent to the outputterminal 432 on the other hand to be output as a digital video signaltherefrom.

Next, explanation will be made of the high-speed reproduction. The servocontrol circuit 360 controls the cylinder motor and the capstan motor sothat a predetermined cylinder rotation speed and a predetermined tapespeed adapted for the high-speed reproduction are provided. A signalreproduced by the magnetic heads 372 and 372' is input to thereproducing system signal processing circuit 380. In the reproducingsystem signal processing circuit 380, a signal processing such asdemodulation for reproduction, channel synthesis, error detection anderror correction are performed at predetermined processing clocksadapted for the high-speed reproduction. Thereafter, the high-speedreproduction signal is supplied to the terminal 390a of the change-overcircuit 390. In the change-over circuit 390, a change-over to connectthe terminal 390a and a terminal 390b is made upon high-speedreproduction. Thereby, the high-speed digital video signal is outputfrom the output terminal 433.

A further embodiment of the present invention will be explained by useof FIG. 9. The construction of the present embodiment is similar to thatof the embodiment shown in FIG. 7 but is different therefrom in that thechange-over circuit 340 is placed at a different position, thechange-over circuit 390 used in FIG. 7 is eliminated and a change-overcircuit 345 is newly added.

An input/output signal upon standard-speed recording/reproduction in thepresent embodiment is the same as that in the embodiment shown in FIG.7. As for high-speed recording and high-speed reproduction, however, thepresent embodiment is different from the embodiment of FIG. 7 in thatthe transmission of a high-speed digital video signal is made in theform of a recording format. Accordingly, upon high-speed recording, thehigh-speed digital video signal is not passed through a recording systemsignal processing circuit 350 but is recorded onto a tape through thechange-over circuit 340 as it is. Upon high-speed reproduction, areproduced signal is subjected to a signal processing for reproductionsuch as error detection and error correction by a reproducing systemsignal processing circuit 380 and is thereafter input to a terminal 345bof the change-over circuit 345. The signal supplied through thechange-over circuit 345 to the recording system side signal processingcircuit 350 is subjected to a signal processing for recording such asaddition of error correction code and modulation for recording by thesignal processing circuit 350 to form a recording format and isthereafter output as a high-speed digital video signal from an outputterminal 433.

The embodiments shown in FIGS. 7 and 9 have feature that high-speedrecording and high-speed reproduction are possible. The best use of thisfeature can be made for dubbing or data communication with the result ofeffective shortening of a dubbing time, a data communication time or adata circuit line occupation time. Also, though those embodiments havebeen mentioned in conjunction with an example in which all ofstandard-speed recording, high-speed recording, standard-speedreproduction and high-speed reproduction modes are involved, it is notnecessarily required to implement all of those modes. There may beconsidered an example in which only a necessary mode is provided incompliance with the purpose of use. FIG. 10 shows an embodiment in whicha high-speed recording function is provided as a recording mode and atleast a high-speed reproduction function is provided as a reproductionmode. Also, there may be considered an embodiment as a system for theexclusive use for reproduction in which at least a high-speedreproduction function is provided, as shown in FIG. 11. Further, FIG. 12shows an embodiment in which a high-speed recording function is providedas a recording mode and a standard-speed reproduction function isprovided as a reproduction mode.

FIG. 13 is a block diagram of one example of the magneticrecording/reproducing system of the embodiment of FIG. 7 for explainingprocessings subsequent to the compression processing. In FIG. 13,reference numeral 201 denotes a synchronization detection circuit,numeral 204 a recording modulation circuit, numeral 205 a cylinder servocontrol circuit, numeral 206 a capstan servo (or tape speed) controlcircuit, numeral 207 a reproduction reference signal generation circuit,numeral 210 a demodulation circuit, numeral 211 a cylinder, numeral 212a pair of recording heads, numeral 213 a pair of reproducing heads,numeral 214 a capstan which controls the tape speed, numeral 215 amagnetic tape, numeral 216 a delivery reel, and numeral 217 a take-upreel. FIG. 14 is a timing chart of input and output signals in theexample shown in FIG. 13 and schematically illustrate a compressedpicture signal 251 which is an input signal, a synchronizing signal 252of the picture signal, a standard-speed reproduction signal 255 which isan output signal, and a reproduction synchronizing signal 256.

In the shown example, Xn speed recording is realized by making a tapespeed and a cylinder rotation speed upon recording n times as high asthose upon standard-speed reproduction. As shown in FIG. 14, thecompressed video signal as an input signal of the circuit shown in FIG.13 and the synchronizing signal include information 251 for n picturesand n synchronizing pulses 252 synchronous therewith in a time when onepicture is reproduced at a standard speed. The picture information isconverted into a predetermined recording format by the recordingmodulation circuit 204 and is recorded onto the magnetic tape 215 by therecording heads 212. At this time, a synchronizing signal for thecylinder servo control circuit 205 and the capstan servo control circuit206 is increased by n times in compliance with the n-tuple speed videosignal, as shown by 252 in FIG. 14, so that the rotation speed of thecylinder 211 and the feed speed of the magnetic tape 215 are increasedby n times. Thereby, the recording onto the tape can be made withsubstantially the same recording format as that in the case of thestandard-speed recording. Upon reproduction, a synchronizing signal forthe cylinder servo control circuit 205 and the capstan servo controlcircuit 206 is supplied from the reproduction reference signalgeneration circuit 207 to restore the cylinder rotation speed and thetape feed speed to those upon standard-speed reproduction, and a signalread by the reproducing heads 213 is demodulated by the demodulationcircuit 210 and is output therefrom. In the circuit shown in FIG. 13, ifthe input video signal and the synchronizing signal are ones of standardspeed, standard-speed recording is possible. Also, Xn speed reproductionis possible if the frequency of an output signal from the reproductionreference signal generation circuit is increased by n times.

FIG. 15 is a block diagram of another example of the magneticrecording/reproducing system of the embodiment of FIG. 7 for explainingprocessings subsequent to the compression processing. FIG. 16 is atiming chart of input and output signals in the example shown in FIG.15. In FIG. 15, the same reference numerals as those used in FIG. 13denote the same or equivalent components as or to those shown in FIG.13. In FIG. 15, reference numeral 202 denotes a÷m circuit, numeral 203recording system memories, numeral 208 a÷m circuit, and numeral 209reproducing system memories. In FIG. 16, the same reference numerals asthose used in FIG. 14 denote the same or equivalent signals as or tothose shown in FIG. 14. In FIG. 16, reference numeral 253 denotesoutputs of the recording system memories 203 and numeral 254 denotes anoutput of the÷m circuit 208 or a synchronizing signal divided by m.

The embodiment shown in FIG. 15 is an example in which m pairs ofrecording heads are used to simultaneously record magnetic signals for mpictures on m tracks, thereby realizing high-speed recording whilesuppressing an increase in the cylinder rotation speed. Uponreproduction, m pairs of reproducing heads are used. Though FIG. 15shows the case where two pairs of recording heads 212 are used tosimultaneously record information for two pictures on two tracks, threeor more pairs of heads can be used in a similar manner.

FIG. 17 is a table showing some examples of the tape speed and thecylinder rotation speed (rpm) in the embodiments shown in FIGS. 13 and15. In the table, high-speed recording or reproduction at a speed tentimes as high as the standard speed is shown by way of example. Designfor implementing another high-speed recording or reproduction issimilarly possible. In the table shown in FIG. 17, examples 1, 2 and 3correspond to the embodiment shown in FIG. 13 and examples 4 and 5correspond to the embodiment shown in FIG. 15.

A still further embodiment of a digital signal recording/reproducingsystem of the present invention will be explained by use of a blockdiagram shown in FIG. 18.

In FIG. 18, reference numeral 501 denotes a signal input terminal towhich a plurality of video signals are input in a time-divisionmultiplex form, numeral 502 a recording selection signal input terminalto which a recording selection signal for selecting one or pluralsignals to be recorded from the multiplexed input signal is input,numeral 503 a recording signal selection circuit for selecting thesignals to be recorded from the multiplexed input signal in accordancewith the recording selection signal from the input terminal 502, numeral504 a recording signal processing circuit for subjecting the selectedsignals to a digital processing for recording onto a recording medium,numerals 505 and 505' magnetic heads, numeral 506 a rotating drum,numeral 507 a magnetic tape or the recording medium, numeral 508 a servocircuit for controlling the rotation of the drum 506 and the travel ofthe tape 507, numeral 511 a reproduction selection signal input terminalto which a reproduction selection signal for selecting one or pluralsignals to be output as a reproduction signal from among themultiple-recorded and reproduced signals is input, numeral 509 areproduction signal selection circuit for selecting the signals to beoutput as a reproduction signal from among the multiple-recorded andreproduced signals in accordance with the reproduction selection signalfrom the input terminal 511, numeral 510 a reproduction signalprocessing circuit for subjecting the selected signals to a digitalprocessing, and numeral 512 a reproduction signal output terminal.

The time-division multiplexed input video signal from the signal inputterminal 501 is supplied to the recording signal selection circuit 503.The recording signal selection circuit 503 is also supplied with therecording selection signal from the recording selection signal inputterminal 502 to make the selection of signals to be recorded. Forexample, in the case where six kinds of video signals A, B, C, D, E andF are input in a time-division multiplex form as shown in (a) of FIG. 19and four signals A, B, C and D thereof are to be selected and recorded,an output of the recording signal selection circuit 503 is as shown in(b) of FIG. 19. Such an output signal of the recording signal selectioncircuit 503 is input to the recording signal processing circuit 504which in turn performs a signal processing for recording such asaddition of error correction code. Also, the recording signal selectioncircuit 503 produces a speed control signal on the basis of the numberof signals in the time-division multiplexed input video signal, thetransmission rate of the input signal and the number of signals to berecorded which are selected by the recording selection signal. The speedcontrol signal is supplied to the recording signal processing circuit504 and the servo circuit 508. For example, in the case where the inputvideo signal is time-division multiplexed to sextuplet with each of sixsignals in the multiplexed input signal being transmitted at a ratetime-base compressed to 1/6 and four signals among the six signals inthe multiplexed input signal are to be selectively recorded, a signalindicative of a quadruple speed is produced as the speed control signal.Also, in the case where the input video signal is time-divisionmultiplexed to sextuplet with each of six signals in the multiplexedinput signal being transmitted at a rate time-base compressed to 1/12and four signals among the six signals in the multiplexed input signalare to be selectively recorded, a signal indicative of a octuple speedis produced as the speed control signal. Namely, in the case where aninput signal is multiplexed to N-plet, the compression rate of each ofthe N signals in the multiplexed input signal is 1/K and the number ofsignals to be selectively recorded is L, a speed control signalindicative of an (L×K)/N-tuple speed is produced. The operating speed ofthe recording signal processing circuit 504 which processes a signalfrom the recording signal selection circuit 503, is changed inaccordance with the speed control signal. For example, in the case of aspeed control signal indicative of a quadruple speed, the recordingsignal processing circuit 504 performs a signal processing at a speedfour times as high as a normal speed and supplies the processed signalto the magnetic heads 505 and 505'. Here, for example, in the case wherethe input video signal is time-division multiplexed to sextuplet witheach of the six signals in the multiplexed input signal beingtransmitted at a rate time-base compressed to 1/6 and a speed controlsignal indicative of a quadruple speed is used to selectively recordfour signals from among the six signals, the speed of an input signalinput to the recording signal processing circuit 504 is four times ashigh as that of one video signal having a normal speed and the recordingsignal processing circuit 504 processes this quadruple-speed inputsignal at a quadruple speed and supplies the processed signal to themagnetic heads, thereby making it possible to record all of the fourselected signals. Also, if the recording signal selection circuit 503 isconstructed so that signals to be selectively recorded are sequentiallychanged for every one track on the tape, compatibility can be held inregard to the number of signals to be selectively recorded and aprocessing speed by causing the recording signal processing circuit 504to perform a completed processing for every one track. In the following,explanation will be made in conjunction with the case where each videosignal is recorded in such a form completed for every track. However, itshould be noted in advance that the present invention is applicable toanother recording system, for example, a system in which signals arerecorded in a form changed for every pixel, line or field. On the otherhand, the servo circuit 508 supplied with the speed control signalindicative of the quadruple speed controls the rotation speed of therotating drum 506 so that it becomes four times as high as a normalspeed and the travel speed of the magnetic tape 507 so that it becomesfour times as high as a normal speed. Thereby, four signals A, B, C andD are alternately recorded on successive tracks of the magnetic tape507, as shown in FIG. 20. According to the control mentioned above, thepattern of recording tracks on the tape becomes the same irrespective ofthe number of signals in the multiplexed input signal, the transmissionrate of each signal and the number of signals to be selectivelyrecorded. In order to make a control upon reproduction easy, it ispreferable that the number of selectively recorded signals and theidentification codes or signal numbers thereof (for example, A, B, C andD or 0, 1, 2 and 3) are recorded as an ID signal for every track.

In the above example, the recording of the time-division multiplexedsignal has been mentioned. However, it is needless to say that thepresent invention is also applicable to the case where the number ofmultiplex signal components in an input video signal is 1 or the inputvideo signal is not multiplexed. In such a case, since the recordingsignal processing circuit 504 and the servo circuit 508 operate atspeeds proportional to the transmission rate of the input video signal,an effect is manifested, for example, in high-speed dubbing. As apparentfrom the foregoing explanation of the operation, it is of course that amultiplexed signal can be recorded at a high speed.

Upon reproduction, a signal reproduced from the magnetic tape 507 by themagnetic heads 505 and 505' mounted on the rotating drum 506 is input tothe reproduction signal selection circuit 509. The reproduction signalselection circuit 509 produces a speed control signal, for example, bydetecting the number of multiple-recorded signals from the ID signalincluded in the reproduced signal and sends the speed control signal tothe servo circuit 508. The speed control signal is a signal indicativeof a speed four times as high as the normal reproduction speed in thecase where the number of multiple-recorded signals is 4 and a signalindicative of a sextuple speed in the case where it is 6. In the case ofthe quadruple speed, the servo control circuit 508 supplied with thespeed control signal indicative of the quadruple speed controls therotation speed of the rotating drum 506 so that it becomes four times ashigh as a normal speed and the travel speed of the magnetic tape 7 sothat it becomes four times as high as a normal speed. Thereby, allsignals recorded can be traced so that the recording track pattern onthe tape becomes the same irrespective of the number of signals to beselectively recorded. In a system which does not have a signalindicative of the number of selectively recorded signals, there may beemployed a method in which the speed control signal is manually set. Ina system in which the number of signals to be recorded on the tape isfixed, the speed control signal has a fixed value. The reproductionsignal selection circuit 509 receives a reproduction selection signalinput from the reproduction selection signal input terminal 511 toselect a desired signal(s) from among the signals reproduced by themagnetic heads 505 and 505' and to output the selected signal as areproduction signal to the reproduction signal processing circuit 510.The reproduction signal selection circuit 509 also outputs a selectionnumber signal indicative of the number of selected signals to thereproduction signal processing circuit 510.

The reproduction signal processing circuit 510 performs a signalprocessing such as code error correction processing and picture signalprocessing for the reproduction signal at a processing speedcorresponding to the selection number signal and outputs the processedreproduction signal from the output terminal 512. For example, in thecase where the number indicated by the selection number signal is 2, thesignal processing speed is two times as high as a normal speed andvarious processings are performed for each selected signal. For example,in the case where signals A and C are selected, the signals A and C areoutput alternately for each field. In the case where the numberindicated by the selection number signal is 1, for example, when thereproduction selection signal from the reproduction selection signalinput terminal 511 selects only the signal C, the reproduction signalprocessing circuit 510 performs the signal processing at the normalspeed to output the signal as reproduced at a normal speed. As apparentfrom the above, the present embodiment makes it possible tosimultaneously record any number of signals selected from among aplurality of signals in a multiplexed video signal and to simultaneouslyreproduce any number of signals from among the recorded signals.

In the case where a plurality of signals are simultaneously reproduced,a construction for outputting the reproduced signals from separateoutput terminals simultaneously and in parallel may be employed,particularly, in the case of an analog output, as a method other thanthe construction in which the plurality of reproduced signals are outputin a time-division multiplex form, as mentioned above. Though in theabove-mentioned example the reproduction signal is output at areproduction speed for a usual video signal, the transmission rate ofthe reproduction signal may be made higher than the reproduction speedfor the usual video signal in order to transmit the reproduction signalto another system in an analog or digital signal form at a high rate orto perform high-speed dubbing which is one of effects of the presentembodiment. This can be realized in such a manner that the fundamentaloperating speed of there producing system is set to be higher than anormal reproduction speed and the operating speeds of the servo circuit508, the reproduction signal selection circuit 509 and the reproductionsignal processing circuit 510 are changed in accordance with the numberof multiple-recorded signals and/or the number of signals to beoutputted as a reproduction signal with the above fundamental speedbeing the standard. If the transmission rate of a reproduction signal ismade variable so that a rate adapted for a transmission path to whichthe reproduction signal is to be connected or the performance orfunction of a recorder by which the reproduction signal is to berecorded, can be selected.

As mentioned above, according to the present embodiment, it is possibleto simultaneously record any number of signals selected from among aplurality of signals in a multiplexed video signal and to reproduce anynumber of signals from among the recorded signals at any speed. Also, inthe case where a plurality of signals are selected and reproduced andthe plurality of reproduced signals are simultaneously output in atime-division multiplex form or from separate output terminals inparallel, it is possible to arbitrarily set the transmission rate of anoutput signal.

The present embodiment has been explained in conjunction with the casewhere the present invention is applied to a helical-scandigital-recording VTR. It is of course that a similar effect can beobtained in the case where the present invention is applied to a fixedhead VTR. The fixed head system is convenient for the structuring of asystem since it has a higher degree of freedom for the setting of theunits of division of a signal subjected to time-division multiplerecording as compared with the helical scan system. Also, it is ofcourse that the present invention is applicable to arecording/reproducing equipment other than the VTR or is applicable to adigital signal processing and analog recording system.

The present invention can be applied to not only the case where an inputsignal is time-division multiplexed, as mentioned above, but also thecase where a plurality of signals are input simultaneously and inparallel. In the latter case, the recording signal selection circuit 503is constructed to receive the input signals in parallel.

As has been mentioned in the foregoing, according to the presentinvention, it is possible to realize a digital VTR in which high-speedrecording onto a tape can be made with the same format as that used instandard-speed reproduction. Further, there can be realized atransmission signal processing for transmitting at a high rate a videosignal to be recorded by such a digital VTR. Also, in the case where asignal transmitted from the transmission signal processing system is tobe recorded by a multiplicity of VTR's, it is possible to designatethose ones of the multiplicity of VTR's by which recording is to be madeand to make a control of the start/stop of recording.

We claim:
 1. A digital signal recording/reproducing system in whichplural kinds of digital signals transmitted in a time-division multiplexform on the same transmission path are recorded/reproduced onto/from arecording medium, comprising:first selection means for selecting one orplural desired signals from a multiplexed input digital signal;recording signal processing means for subjecting the input signal to apredetermined signal processing for recording at a predeterminedprocessing clock in accordance with a transmission rate on thetransmission path, the number of signals in the multiplexed input signaland the result of selection by said first selection means; secondselection means for selecting, in the case where plural kinds of signalsare multiple-recorded on the recording medium by means of said firstselection means and said recording signal processing means, one orplural desired signals from among the plural kinds of multiple-recordedsignals upon reproduction; control means for setting a driving speed ofthe recording medium to a desired speed in accordance with thetransmission rate on the transmission path, the number of signals in themultiplexed input signal and the result of selection by said firstselection means or the number of multiple-recorded signals; andreproduction signal processing means for performing a signal processingfor reproduction at a predetermined processing clock in accordance withthe result of selection by said second selection means, wherebyrecording is made with a predetermined signal processing clock and apredetermined recording medium driving speed being set so that arecording signal format on the recording medium becomes the same nomatter what the multiplexed input signal and the selection of signals tobe recorded may be, and reproduction is made with a predetermined signalprocessing clock and a predetermined recording medium driving speedbeing set upon reproduction in accordance with the number of signals tobe reproduced which are selected by said second selection means and thenumber of multiple-recorded signals which are selected by said firstselection means.
 2. A digital signal recording/reproducing systemaccording to claim 1, wherein said recording medium includes a magnetictape, signals are recorded/ reproduced onto/from a helical track on saidmagnetic tape by a rotating head, and said control means controls uponrecording the rotation speed of a drum having said rotating head mountedthereon and the driving speed of said magnetic tape so that they becomepredetermined speeds proportional to the transmission rate of themultiplexed input signal and the number of signals to be recorded whichare selected by said first selection means and inversely proportional tothe number of signal in the multiplexed input signal and controls uponreproduction those speeds so that they become predetermined speedsproportional to the number of signals multiple-recorded on said magnetictape.
 3. A digital signal recording/reproducing system according toclaim 1, wherein said reproduction signal processing means includes aplurality of output means for simultaneously outputting in parallel theplural signals selected by said second selection means.